Download attachment on basis of attachment id - struts2

Question

I have a table which stores attachments uploaded by the users. The attachments can be of type text/doc/jpg etc. Also there would be multiple users uploading files. So there are chances that the file name may be same is some cases. So when this happen the file which is first in the DB table gets downloaded. So along with the file name can one more parameter be added to ensure that correct file is getting downloaded. That other parameter could be the attachment_id which is unique in each case.
This is the action method used to download file on basis of its name
public String downloadAttachFile() throws FileNotFoundException {
attachFileName = ServletActionContext.getRequest().getParameter("myFileFileName");
fileInputStream = new FileInputStream(new File(AttachFileName));
return SUCCESS;
}
Thanks In advance.

Answer 1

Not sure where your files are (file system ?) and how can they be stored with the same name (different folders ?), nor when / how you download multiple files at a time, but you just need to replicate the OS mechanism to rename multiple files with the same name with (n) at the end, like foo.txt and foo(1).txt.
Feel free to adapt the function I've written in the answer to my own ZIP question:
// Set-up a list of filenames to prevent duplicate entries
HashSet<String> entries = new HashSet<String>();
/* ====== ====== ====== ====== ====== ====== ====== ====== ====== ====== ======
then call getUniqueFileName() for each file passing "entries" as parameter
to get an unique file name.
====== ====== ====== ====== ====== ====== ====== ====== ====== ====== ====== */
private String getUniqueFileName(HashSet<String> entries, String completeFileName){
if (entries.contains(completeFileName)){
int extPos = completeFileName.lastIndexOf('.');
String extension = extPos>0 ? completeFileName.substring(extPos) : "";
String partialFileName = extension.length()==0 ? completeFileName : completeFileName.substring(0,extPos);
int x=1;
while (entries.contains(completeFileName = partialFileName + "(" + x + ")" + extension))
x++;
}
entries.add(completeFileName);
return completeFileName;
}